1. Field of the Invention
The invention relates to the central hub of a bicycle wheel. It also relates to a bicycle wheel equipped with such a hub.
2. Description of Background and Relevant Information
In a conventional construction, a bicycle wheel has a central hub through which the wheel and the bicycle frame.
Recently, efforts have been made to reduce the weight of the wheel for improving the inertial behavior of the wheel.
In this regard, patent document EP 1 084 868 and U.S. Pat. No. 6,402,256 teach that one can decrease the thickness of the lower bridge of the rim between two consecutive zones for fastening the spokes in order to decrease the weight of the rim without substantially affecting the rigidity and the strength of the wheel.
Likewise, patent documents EP 1 231 047 and U.S. Pat. No. 6,688,704 describe a method of making a rim from a carbon fiber material, and EP 1 231 077 and U.S. Published Application Publication No. 2002/0108249 describe a method of making a hub body from a carbon fiber material.
Indeed, a composite structure made of carbon fiber is lighter than a metallic structure, because carbon has a density that is less than that of aluminum, for example, and a higher modulus of compression. However, one cannot perform machinings, such as a threading or tapping, with a carbon element.
The patent document EP 1 110 754 and U.S. Pat. No. 6,375,273 describe a hub having three elements, two lateral flanges and a central portion. These three elements can be made from various materials. In particular, one can infer therefrom that the central portion can be made from a material that is lighter than the lateral flanges in order to reduce weight.